Partial fragments of nuclear 185 rDNAs from morphologically wide and narrow thalli of the seaweed Porphyra pseudolineazis were amplified and sequenced to compare their DNA homology. Both sequences of 311 base pairs showed $100{\%}$ identical each other. They showed $97.7{\%}$ similarity with a wild strain collected at Sodol in Kangwondo, and $99.4{\%}$ similarity with the GenBank accession number AB013185 of the Japanese P. pseudolinearis. Thus the morphological difference of wide and narrow blades might not be a classification criterion for the sub-species level of P. pseudolinearis.